The invention relates to an injection molding tool including at least one hot channel nozzle to which melt is supplied via a hot channel which, at its end remote from the hot channel nozzle, includes an inlet opening which can be closed by a closure element which extends axially through an inlet part of the hot channel adjacent the supply opening wherein, at its end remote from the inlet opening, the hot channel is angled and the closure element extends through the wall of the hot channel for actuation of the closure element by an operating element disposed outside the hot channel.
Such an injection molding tool is well-known in the state of the art and is manufactured and sold for example by the Assignee of the present application with great success. However, in the known injection molding tool, the melt is always conducted from an injection molding machine arranged at the side of the injection molding tool via an admission opening into an inlet part of a hot channel which extends into the interior of the injection molding tool. At its end remote from the inlet opening the inlet part of the hot channel is angled. By means of the hot channel structure, the melt is distributed to the respective hot channel nozzles.
For the transfer of the melt, the supply nozzle of the injection molding machine is placed in tight contact with the input part of the hot channel. Since the supply nozzle has to be removed from the injection molding tool during operation, for example, during the removal of the manufactured injection molding parts from the injection molding tool, the supply nozzle is not disposed on the inlet opening for a certain period so that melt can flow out of the supply nozzle because of a backflow of melt.
Melt flowing out of the nozzle however can result in large manufacturing problems. It is therefore advantageous if also the supply opening can be closed by a closure member like the outlet opening of the hot channel nozzle. The closure member is for example a valve needle which extends about axially through the inlet part of the hot channel and protrudes through the angled wall of the inlet part of the hot channel. At the end of the closure needle, which projects from the hot channel, an operating device is provided which comprises generally a pneumatic or hydraulic operating cylinder. Because of the high pressure prevalent in the hot channel the seals at the penetration area of the valve needle through the wall must comply with high sealing requirements. Leakages could result in a breakdown of manufacturing operations.
Since the inlet part of the hot channel extends into the interior of the injection molding tool, the place where the closure needle extends through the wall of the hot channel and the operating element are disposed in the interior of the injection molding tool. This is highly disadvantageous since, consequently, the penetration seals and the operating device are not easily accessible from the outside. As a result, maintenance or repair work for eliminating a defect by an exchange of faulty components is generally only possible upon disassembly of the injection molding tool. This however results often in undesirably long downtimes of the injection molding tool for servicing or repair work. Furthermore, the known arrangement is of a relatively complicated design.
It is therefore the object of the present invention to provide an injection molding tool of the type as described above, wherein however servicing and/or repair of the closure elements for the melt admission opening are facilitated.